vop_rename(9)

NAME

VOP_RENAME - rename a file

SYNOPSIS

#include <sys/param.h>
#include <sys/vnode.h>
int
VOP_RENAME(struct vnode *fdvp, struct vnode *fvp,
        struct componentname *fcnp, struct vnode *tdvp,
        struct vnode *tvp, struct componentname *tcnp);

DESCRIPTION

This renames a file and possibly changes its parent directo

ry. If the
destination object exists, it will be removed first.

Its arguments are:

fdvp The vnode of the old parent directory.

fvp The vnode of the file to be renamed.

fcnp Pathname information about the file's current name.

tdvp The vnode of the new parent directory.

tvp The vnode of the target file (if it exists).

tcnp Pathname information about the file's new name.

LOCKS

The source directory and file are unlocked but are expected

to have their
ref count bumped on entry. The VOP routine is expected to

vrele(9) both
prior to returning.

The destination directory and file are locked as well as

having their ref
count bumped. The VOP routine is expected to vput(9) both

prior to
returning.

PSEUDOCODE

int
vop_rename(struct vnode *fdvp, struct vnode *fvp, struct

componentname *fcnp,

struct vnode *tdvp, struct vnode *tvp, struct

componentname *tcnp)

{

int doingdirectory = 0;
int error = 0;

/*

* Check for cross-device rename.
*/

if (fvp->v_mount != tdvp->v_mount) {

error = EXDEV;

abortit:

if (tdvp == tvp)

vrele(tdvp);

else

vput(tdvp);

if (tvp)

vput(tvp);

vrele(fdvp);
vrele(fvp);
return error;

}

if (tvp exists and is immutable) {

error = EPERM;
goto abortit;

}

/*

* Check if just deleting a link name.
*/

if (fvp == tvp) {

if (fvp->v_type == VDIR) {

error = EINVAL;
goto abortit;

}

/*

* Release destination.
*/

vput(tdvp);
vput(tvp);

/*

* Delete source. Pretty bizarre stuff.
*/

vrele(fdvp);
vrele(fvp);
fcnp->cn_flags &= ~MODMASK;
fcnp->cn_flags |= LOCKPARENT | LOCKLEAF;
fcnp->cn_nameiop = DELETE;
VREF(fdvp);
error = relookup(fdvp, &fvp, fcnp);
if (error == 0)

vrele(fdvp);

return VOP_REMOVE(fdvp, fvp, fcnp);

}

if (fvp is immutable) {

error = EPERM;
goto abortit;

}

error = VOP_LOCK(fvp);
if (error)

goto abortit;

if (vp is a directory) {

/*

* Avoid ".", "..", and aliases of "." for obvious

reasons.
*/

if ((fcnp->cn_namelen == 1 && fcnp->cn_nameptr[0] ==

|| fdvp == fvp
|| ((fcnp->cn_flags | tcnp->cn_flags) & ISDOT

DOT)) {
VOP_UNLOCK(fvp);
error = EINVAL;
goto abortit;

}
doingdirectory = 1;

}
vrele(fdvp);

/*

* Bump link count on fvp while we are moving stuff

around. If we
* crash before completing the work, the link count may

be wrong
* but correctable.
*/

...;

/*

* If ".." must be changed (ie the directory gets a new
* parent) then the source directory must not be in the
* directory hierarchy above the target, as this would
* orphan everything below the source directory. Also
* the user must have write permission in the source so
* as to be able to change "..".
*/

error = VOP_ACCESS(fvp, VWRITE, tcnp->cn_cred, tc

np->cn_thread);
VOP_UNLOCK(fvp);
if (doingdirectory && fdvp != tdvp) {

/*

* Check for pathname conflict.
*/

...;

}

/*

* If the target doesn't exist, link the target to the

source and
* unlink the source. Otherwise, rewrite the target di

rectory to
* reference the source and remove the original entry.
*/

if (tvp == NULL) {

/*

* Account for ".." in new directory.
*/

if (doingdirectory && fdvp != tdvp) {

/*

* Increase link count of tdvp.
*/

...;

}

/*

* Add name in new directory.
*/

...;

if (error) {

if (doingdirectory && fdvp != tdvp) {

/*

* Decrease link count if tdvp.
*/

...;

}
goto bad;

}
vput(tdvp);

} else {

/*

* Target must be empty if a directory and have no

links
* to it. Also, ensure source and target are compat

ible
* (both directories, or both not directories).
*/

if (tvp is a directory) {

if (tvp is not empty) {

error = ENOTEMPTY;
goto bad;

}
if (!doingdirectory) {

error = ENOTDIR;
goto bad;

}
/*

* Update name cache since directory is going

away.
*/

cache_purge(tdvp);

} else if (doingdirectory) {

error = ENOTDIR;
goto bad;

}

/*

* Change name tcnp in tdvp to point at fvp.
*/

...;

/*

* If the target directory is in same directory as

the source
* directory, decrement the link count on the parent

of the
* target directory. This accounts for the fact

that a
* directory links back to its parent with "..".
*/

if (doingdirectory && fdvp == tdvp) {

/*

* Decrement link count of tdvp.
*/

...;

}
vput(tdvp);

/*

* Decrement the link count of tvp since the direc

tory no
* longer points at it.
*/

...;
if (doingdirectory) {

/*

* Clean up the old directory tvp.
*/

...;

}
vput(tvp);

}

/*

* Unlink the source. If a directory was moved to a new

parent,
* update its ".." entry. Gobs of ugly UFS code omitted

here.
*/

...;

bad:

if (tvp)

vput(tvp);

vput(tdvp);

out:

if (VOP_LOCK(fvp) == 0) {

/*

* Decrement link count of fvp.
*/

...;
vput(fvp);

} else

vrele(fvp);

return error;

}

ERRORS

[EPERM] The file is immutable.

[EXDEV] It is not possible to rename a file be

tween different

file systems.

[EINVAL] An attempt was made to rename . or .., or

to perform

an operation which would break the direc

tory tree
structure.

[ENOTDIR] An attempt was made to rename a directory

to a file or

vice versa.

[ENOTEMPTY] An attempt was made to remove a directory

which is not

empty.

SEE ALSO

vnode(9)

AUTHORS

This manual page was written by Doug Rabson.

BSD July 24, 1996

BSD